Hydrophilic anti-corrosion integrated coating and preparation method thereof

Abstract

The invention discloses a hydrophilic anti-corrosion integrated coating and a preparation method thereof, and relates to the field of coating preparation, the preparation method comprises the following steps: carrying out hydrolysis reaction on various trimethoxysilanes in an acidic aqueous solution to obtain a silanol solution with silicon hydroxyl; sequentially adding a silanol solution and a catalyst into the hybrid emulsion, and stirring to obtain a composite coating; the surface of a base material is pretreated, so that the surface of the base material has active hydroxyl groups, and the base material is coated with the composite coating to form a wet film; and after the base material coated with the wet film is pre-cured, heating curing is conducted, and after curing is completed, the hydrophilic anti-corrosion integrated coating is formed on the base material. Through the mode, the core defect that the hydrophilic component is easy to dissolve out and lose due to weak interface bonding is overcome, the possibility that micropores are generated and a coating is damaged due to loss is avoided through chemical fixation of the hydrophilic component, and the durability of the hydrophilic function and the integrity of corrosion prevention are synchronously guaranteed; the problem of mutual restriction of hydrophilicity and corrosion resistance is solved.

Description

Technical Field

[0001] This invention relates to the field of coating preparation, and in particular to a hydrophilic and anti-corrosion integrated coating and its preparation method. Background Technology

[0002] Hydrophilic anti-corrosion coatings are cutting-edge protective materials that endow substrates with dual functions through material design and surface engineering. They introduce hydrophilic components or construct special surface structures into traditional anti-corrosion resins, enabling the coating to achieve functions such as rapid wetting, anti-fogging, and self-cleaning, while effectively blocking corrosive media from eroding metals. The core technology lies in resolving the contradiction between hydrophilicity and corrosion resistance. Common implementation paths include organic-inorganic hybridization, nanocomposite, and chemical grafting. This coating is highly effective in improving heat exchange efficiency and reducing corrosion risk, and is widely used in medical devices, marine equipment, air conditioning heat exchangers, and other fields.

[0003] In existing technologies, in applications such as metal heat exchangers and medical devices that require both surface hydrophilicity and long-term corrosion protection, hydrophilic anti-corrosion coatings generally employ physical blending or surface adsorption to introduce hydrophilic agents into the anti-corrosion coating system. This method aims to achieve rapid wetting or anti-fogging functions through hydrophilic components, while relying on the resin matrix to provide a corrosion barrier. However, after use, this method suffers from the problem of loss of physically blended hydrophilic components due to weak interfacial bonding, leading to the simultaneous accelerated failure of both the hydrophilicity and anti-corrosion properties of the coating. Specifically, due to the weak chemical bonding between the hydrophilic components and the hydrophobic resin matrix, they are prone to dissolution and loss in the service environment. This loss not only directly leads to a rapid decline in the hydrophilicity of the coating but also leaves micropores or channels in situ within the coating. These newly formed microscopic defects destroy the compactness of the anti-corrosion coating, becoming preferential pathways for the penetration of water, oxygen, and corrosive ions, thereby drastically accelerating the corrosion process of the base metal. Ultimately, this vicious cycle of structural defects induced by the loss of hydrophilic components, which in turn leads to protective failure, severely limits the service life and reliability of existing hydrophilic anti-corrosion coatings in harsh environments.

[0004] Therefore, a hydrophilic and anti-corrosion integrated coating and its preparation method are proposed to solve the problem that the hydrophilic components of physically blended coatings are lost due to weak interfacial bonding, which leads to the simultaneous accelerated failure of the coating's hydrophilicity and anti-corrosion properties. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated hydrophilic and anti-corrosion coating and its preparation method, which solves the problem that the hydrophilic components of physically blended coatings are lost due to weak interfacial bonding, leading to the simultaneous accelerated failure of the coating's hydrophilic and anti-corrosion properties.

[0006] To achieve this objective, the present invention adopts the following technical solution: A method for preparing an integrated hydrophilic and anti-corrosion coating, the method comprising the following steps: Step S1: Hydrolyze various trimethoxysilanes in an acidic aqueous solution to obtain a silanol solution with silanol groups. Then, add the silanol solution and the catalyst to the hybrid emulsion in sequence and stir to obtain a composite coating. Step S2: Pre-treat the surface of the substrate to make it have active hydroxyl groups, and then apply the composite coating to the substrate to form a wet film; Step S3: After pre-curing the substrate coated with wet film, heat it up to cure it. After curing, a hydrophilic and anti-corrosion integrated coating is formed on the substrate.

[0007] The silanol solution is obtained according to the following steps: First, KH-560, PEG-Si and MTMS were added to the reaction vessel, followed by the addition of a mixed solvent. Acetic acid was added dropwise during stirring to adjust the pH of the system to 4.0-5.0. The system was then stirred at 300-600 rpm for 110-130 min at room temperature under this pH value. After stirring, a silanol solution was obtained.

[0008] The molar ratio of KH-560, PEG-Si and MTMS is (2.5-3.5):(4.5-5.5):(1.7-2.3), the mixed solvent includes deionized water and anhydrous ethanol, and the volume ratio of deionized water to anhydrous ethanol is 1:(3.8-4.2), and the concentration of silane in the silanol solution is 20-30wt%.

[0009] The PEG-Si is obtained according to the following steps: Polyethylene glycol and anhydrous tetrahydrofuran were kept at 58-62℃ for 30 min, then the system was cooled to 38-42℃, and isocyanate-based propyltrimethoxysilane was added dropwise over 30 min, followed by the addition of dibutyltin dilaurate catalyst. The system temperature was then raised to 63-67℃ and stirred for 4-6 h. After stirring, the system was cooled to room temperature and evaporated at 45-50℃, then dried in a vacuum environment of 40℃ and ≥0.095 MPa for 24 h to obtain PEG-Si. The molecular weight of polyethylene glycol was 600, the molar ratio of polyethylene glycol to isocyanate-based propyltrimethoxysilane was 1:(2.05-2.25), the mass ratio of anhydrous tetrahydrofuran to polyethylene glycol was (2.5-4.5):1, and the amount of dibutyltin dilaurate catalyst added was 0.05%-0.2% of the mass of polyethylene glycol.

[0010] The composite coating is obtained according to the following steps: The hybrid emulsion is stirred at 300-500 rpm in a dispersion vessel. A silanol solution is added after 5-10 min. After the silanol solution is added, a catalyst is added, and the stirring speed is reduced by 100-200 rpm and stirred for 25-35 min to obtain the composite coating.

[0011] The hybrid emulsion is an aqueous acrylic-siloxane hybrid emulsion with a solid content of 40-60%. Preferably, the aqueous acrylic-siloxane hybrid emulsion is a core-shell structure emulsion obtained by emulsion copolymerization of acrylate monomers and alkoxysilane monomers, wherein the siloxane content accounts for 10-40% of the emulsion solid mass. The catalyst is aluminum acetylacetonate, and the amount of aluminum acetylacetonate added is 0.3%-1.0% of the hybrid emulsion solid mass. The ratio of the total solid mass of silane in the silanol solution to the solid mass of the hybrid emulsion is 1:(1.5-4).

[0012] Step S2 specifically includes the following steps: Step S21: Degrease and clean the metal substrate, and perform sandblasting or phosphating treatment as needed to make its surface clean and have active hydroxyl groups, thus obtaining the first substrate. Step S22: Apply the composite coating evenly to the pretreated substrate using a spraying process to form a wet film with a thickness of 80-100μm on the substrate. After the wet film is formed, let the substrate stand at room temperature for 3-5 minutes to level it, and obtain the second substrate.

[0013] Step S3 specifically includes the following steps: Step S31: Place the second substrate in an oven and heat-cur it at the first temperature for 28-32 minutes, so that the wet film on the second substrate is transformed into a dry gel state. Step S32: After raising the first temperature to the second temperature at a rate of 2-3℃ / min, the second substrate is held at the second temperature for 55-65min, and then naturally cooled to room temperature.

[0014] In step S31, the first temperature is 58-62℃, and in step S32, the second temperature is 118-122℃.

[0015] A hydrophilic and anti-corrosion integrated coating is prepared by the preparation method described above.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a hydrophilic and anti-corrosion integrated coating and its preparation method. The method involves pretreating hydrophilic polyethylene glycol segments with hydrolyzable trimethoxysilane to synthesize a PEG-Si functional monomer with network reaction capabilities. This monomer is then co-hydrolyzed with other silanes to form an active silanol solution, which is then composited with a hybrid emulsion. During subsequent coating and programmed curing, all silane components collectively construct a unified and dense three-dimensional Si-O-Si inorganic-organic hybrid network through hydrolysis and condensation reactions. This allows the hydrophilic PEG segments to co-react through their terminal siloxane structures. The hydrophilic components are chemically anchored within the framework of the coating network via valence bonds, thereby altering their weak binding state, which previously relied on physical blending or surface adsorption. Therefore, this method effectively overcomes the core defect of traditional methods where hydrophilic components are easily dissolved and lost due to weak interfacial bonding. The robust chemical fixation of the hydrophilic components eliminates the possibility of micropores and damage to the coating's density caused by loss, thus simultaneously ensuring the durability of the hydrophilic function and the integrity of the anti-corrosion barrier. This breaks the traditional dilemma of mutual constraint between hydrophilicity and corrosion resistance, significantly improving the long-term service life and reliability of the coating in harsh humid environments. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0019] Figure 1 This is a schematic flowchart of the preparation method in this invention. Detailed Implementation

[0020] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0022] Example 1: Please see Figure 1 This embodiment describes a method for preparing an integrated hydrophilic and anti-corrosion coating, the method comprising the following steps: Step S1: A variety of trimethoxysilanes, including interface-anchored silanes, hydrophilic functional silanes and network crosslinked silanes, are hydrolyzed in an acidic aqueous solution to obtain a silanol solution with silanol groups. The silanol solution and the catalyst are then added to the hybrid emulsion in sequence and stirred to obtain a composite coating. Step S2: Pre-treat the surface of the substrate to make it have active hydroxyl groups, and then apply the composite coating to the substrate to form a wet film; Step S3: After pre-curing the substrate coated with wet film, heat it up to cure it. After curing, a hydrophilic and anti-corrosion integrated coating is formed on the substrate.

[0023] Specifically, in step S1, a variety of trimethoxysilanes undergo a hydrolysis reaction in an acidic aqueous solution to obtain a silanol solution with silanol groups. The silanol solution and the catalyst are then added sequentially to a hybrid emulsion and stirred to obtain a composite coating. The silanol solution is obtained according to the following steps: First, add KH-560 (γ-glycidyl etheroxypropyltrimethoxysilane), PEG-Si (polyethylene glycol-modified trimethoxysilane), and MTMS (methyltrimethoxysilane) to the reaction vessel, followed by the addition of a mixed solvent. Acetic acid is added dropwise during stirring to adjust the pH of the system to 4.0-5.0. The system is then stirred at this pH and at room temperature at 300-600 rpm for 110-130 min. After stirring, a silanol solution is obtained.

[0024] The molar ratio of KH-560, PEG-Si and MTMS is (2.5-3.5):(4.5-5.5):(1.7-2.3), the mixed solvent includes deionized water and anhydrous ethanol, and the volume ratio of deionized water to anhydrous ethanol is 1:(3.8-4.2), and the concentration of silane in the silanol solution is 20-30wt%.

[0025] It should be noted that in the step of obtaining the silanol solution, the material undergoes a chemical and physical transformation from a chemically inert trimethoxysilane monomer to a homogeneous solution rich in highly reactive silanol groups. This step is an acid-catalyzed hydrolysis reaction. When KH-560, PEG-Si, and MTMS are dissolved in a mixed solvent composed of deionized water and anhydrous ethanol, and acetic acid is added to adjust the pH to an acidic environment of 4.0-5.0, hydrogen ions act as a catalyst, attacking the methoxy groups attached to silicon atoms. The methoxy groups gradually detach and are replaced by hydroxyl groups provided by water molecules, thus ultimately converting the three methoxy groups of each silane molecule into three silanol groups. This hydrolysis process is gradual. With stirring, the different silane molecules, which may have been phase-separated or unevenly distributed, are fully mixed and diffused under the co-solvent system and continuous mechanical action, ultimately forming a uniform, stable, transparent or semi-transparent pre-hydrolyzed solution. This step realizes the conversion of stable stored methoxysilanes into a silanol solution that can immediately participate in condensation crosslinking in subsequent steps.

[0026] It is understood that the above steps, by achieving complete and controllable hydrolysis and uniform premixing at the molecular level, pre-construct a highly active and homogeneous precursor solution for the entire coating system, laying a controllable and consistent chemical reaction foundation for the subsequent coating curing process. Specifically, silanol groups are the starting point for all subsequent bonding behaviors, and their activity and quantity directly determine the crosslinking density of the coating network. The above three functional silanes (providing interface anchoring, hydrophilic function, and network crosslinking) are fully mixed in the pre-hydrolyzed solution, which helps to achieve uniform introduction of components in the subsequent coating film, reducing the risk of local phase separation or reaction differences caused by uneven mixing, ensuring that they are introduced simultaneously and in the same place in the subsequent coating film, and avoiding phase separation or uneven reaction caused by sequential addition or excessively high local concentration.

[0027] Understandably, silanol solutions provide a chemical solution to address the problem of loss caused by physical blending of hydrophilic components. Specifically, in traditional physical blending methods, the hydrophilic component and the resin matrix are merely physically mixed, resulting in weak interfacial bonding. However, in this step, the hydrophilic component PEG-Si undergoes a hydrolysis reaction, converting its terminal methoxy groups into active silanol groups with the same chemical properties as the preservative component KH-560 and the crosslinking component MTMS. In the subsequent curing stage, PEG-Si transforms into a structural unit that can participate in network construction through chemical reactions. Together with KH-560 and MTMS, it possesses the same ability to participate in the chemical reaction of building a unified Si-O-Si network. This changes the state of PEG-Si in the system, transforming it from a physical additive into an integrated functional structural unit that can participate in network construction. This lays the foundation for the hydrophilic segments to be firmly anchored in the three-dimensional crosslinked network through covalent bonds.

[0028] It is worth noting that this step uses an acidic aqueous solution hydrolysis process to treat the material, achieving efficient and controllable hydrolysis of trimethoxysilane under mild conditions. The acidic conditions (pH 4.0-5.0) provide moderate catalytic activity, ensuring the hydrolysis reaction proceeds sufficiently to near completion while avoiding premature or excessively rapid condensation reactions caused by excessively low pH, which could lead to gelation or particle formation. This results in a storage-stable pre-hydrolyzed solution. The ratio of KH-560, PEG-Si, and MTMS is (2.5-3.5):(4.5-5.5):(1.7). The mixing of silanes at a molar ratio of -2.3 balances the interfacial bonding, hydrophilicity, and network crosslinking density. In addition, the volume ratio of deionized water to anhydrous ethanol 1:(3.8-4.2) and the total concentration of silanes together determine the polarity and concentration of the hydrolysis reaction medium, ensuring that all silanes are fully dissolved and participate in hydrolysis. Stirring at 300-600 rpm for 110-130 min at room temperature ensures sufficient mass and heat transfer, making the hydrolysis reaction uniform and thorough. Finally, a stable, homogeneous, and transparent silanol solution is obtained, providing a reliable guarantee for the smooth implementation of subsequent steps.

[0029] The PEG-Si is obtained according to the following steps: Polyethylene glycol and anhydrous tetrahydrofuran were kept at 58-62℃ for 30 min, then the system was cooled to 38-42℃, and isocyanate-based propyltrimethoxysilane was added dropwise over 30 min, followed by the addition of dibutyltin dilaurate catalyst. The system temperature was then raised to 63-67℃ and stirred for 4-6 h. After stirring, the system was cooled to room temperature and evaporated at 45-50℃, followed by evaporation under vacuum of ≥0.095 MPa at 40℃. The mixture was dried in an environment for 24 hours to obtain PEG-Si. The polyethylene glycol had a molecular weight of 600, the molar ratio of polyethylene glycol to isocyanate-propyltrimethoxysilane was 1:(2.05-2.25), the mass ratio of anhydrous tetrahydrofuran to polyethylene glycol was (2.5-4.5):1, and the amount of dibutyltin dilaurate catalyst added was 0.05%-0.2% of the polyethylene glycol mass. The dibutyltin dilaurate catalyst was used to catalyze the addition reaction of isocyanate with hydroxyl groups.

[0030] It should be noted that in the PEG-Si acquisition step, the material undergoes a chemical transformation from independent polyethylene glycol molecules and isocyanate-based silane monomers to bipolar silane functionalized hydrophilic segments with defined structures through the addition reaction of isocyanate and hydroxyl groups. This step is based on the formation reaction of urethane bonds, allowing the hydroxyl groups at both ends of polyethylene glycol with a molecular weight of 600 to undergo nucleophilic addition with the highly reactive isocyanate groups in excess isocyanate-based propyltrimethoxysilane molecules under the catalysis of dibutyltin dilaurate. The dibutyltin dilaurate catalyst is first coordinated and activated with the isocyanate groups, and then the hydroxyl groups of polyethylene glycol attack the activated isocyanate. The carbon atom of the ester group, after passing through a tetrahedral intermediate state, eventually forms a stable urethane bond, thus firmly connecting the hydrophilic polyethylene glycol segment to the silane structural unit with three hydrolyzable methoxy groups at the end via covalent bonding. In this process, the reaction is carried out in anhydrous tetrahydrofuran solvent. Initial heating ensures complete dissolution of polyethylene glycol, and then the dropwise addition and reaction temperature are controlled to ensure a stable reaction and avoid side reactions caused by local overheating. Finally, the solvent is removed by evaporation and vacuum drying to obtain a viscous liquid or waxy solid product, namely the target molecule PEG-Si, whose structure simultaneously contains a hydrophilic polyethylene glycol segment and a silane terminus that can subsequently participate in the construction of a hydrolytic condensation network.

[0031] It is known that the PEG-Si preparation step, by achieving precise chemical coupling between hydrophilic segments and reactive silane ends, and ensuring the certainty and high purity of the product molecular structure, serves as a customized, multifunctional integrated monomer for the entire coating system. This gives PEG-Si two key functions: the polyethylene glycol segments of PEG-Si provide durable hydrophilic properties, while the three methoxy groups at the ends of PEG-Si endow the molecule with the same ability as other silanes in the system to participate in the formation of a three-dimensional inorganic-organic hybrid network through hydrolysis and condensation. This transforms the hydrophilic function from an additive that relies on physical adsorption or entanglement into a structural component that can be chemically fixed onto the coating framework. The PEG-Si monomer synthesized in this step is the key foundation for subsequent chemical anchoring of hydrophilic components, thereby overcoming the defects of physical blending.

[0032] Understandably, the PEG-Si acquisition step provides a solution to the problem of hydrophilic components being lost due to weak interfacial bonding at the molecular level. Specifically, in traditional physical blending methods, the hydrophilic agent and the resin matrix have significantly different properties and are only bound by van der Waals forces, making them prone to detachment under media erosion or swelling. However, in this step, by pre-synthesizing PEG-Si, one or both ends of the polyethylene glycol hydrophilic segments are already connected to silane reactive groups through stable urethane covalent bonds. During the preparation of the silanol solution and the curing of the coating, the silane ends in PEG-Si will hydrolyze and condense together with other silanes to form a continuous Si-O-Si network. This indicates that the entire polyethylene glycol hydrophilic segment is embedded in the skeletal network of the coating, and its loss from the coating requires overcoming chemical bonds, which has high stability under normal service conditions. Therefore, this step, through chemical synthesis, combines hydrophilic functionality with network structure, eliminating the possibility of loss at the source.

[0033] It is worth noting that this step employs a stepwise temperature-controlled solution polymerization process to treat the materials, aiming to ensure that the addition reaction between isocyanate and hydroxyl groups is efficient, complete, and with minimal side reactions, thereby obtaining a PEG-Si product with a well-defined structure and high conversion rate. In this step, dissolving polyethylene glycol in anhydrous tetrahydrofuran and preheating ensures complete dissolution of the reactants and an anhydrous system, avoiding side reactions such as the reaction of isocyanate with water to generate amines and carbon dioxide. Subsequently, cooling and controlling the rate of dropwise addition of isocyanate-based silanes are to prevent local temperature runaway due to intense exothermic reactions, thereby reducing side reactions such as isocyanate dimerization or trimerization and ensuring reaction selectivity. Dibutyltin dilaurate catalyst is added at a ratio of 0.05%-0.2% of polyethylene glycol mass to provide... The method achieves moderate catalytic activity, promoting the main reaction while avoiding over-catalysis leading to gelation. The molar ratio of polyethylene glycol to isocyanate-based silane 1:(2.05-2.25) ensures a slight excess of isocyanate, thereby driving the hydroxyl groups at both ends of polyethylene glycol to react as completely as possible, generating the target dual-end modified product. The excess trace amount of isocyanate can be treated in subsequent steps or removed by post-purification. In addition, stirring at 63-67℃ for 4-6 hours provides sufficient reaction time to ensure the conversion rate approaches complete. Finally, the solvent and any possible residual small molecules are thoroughly removed by evaporation and vacuum drying, resulting in a high-purity PEG-Si functional monomer that can be directly used for the subsequent preparation of silanol solutions, ensuring the synthesis quality and consistency of PEG-Si.

[0034] The composite coating is obtained according to the following steps: The hybrid emulsion is stirred at 300-500 rpm in a dispersion vessel. A silanol solution is added after 5-10 min. After the silanol solution is added, a catalyst is added, and the stirring speed is reduced by 100-200 rpm and stirred for 25-35 min to obtain the composite coating.

[0035] The hybrid emulsion is an aqueous acrylic-siloxane hybrid emulsion with a solid content of 40-60%. The catalyst is aluminum acetylacetonate, and the amount of aluminum acetylacetonate added is 0.3%-1.0% of the solid mass of the hybrid emulsion. The ratio of the total solid mass of silane in the silanol solution to the solid mass of the hybrid emulsion is 1:(1.5-4).

[0036] It should be noted that in the process of obtaining the composite coating, the materials undergo a physical mixing and initial interfacial interaction process from multiple independent liquid phases (silanol solution, hybrid emulsion) to a single homogeneous dispersion system. In this step, through physical dispersion and adsorption, when the silanol solution is slowly added to the aqueous acrylic-siloxane hybrid emulsion under stirring, the active silanol hydroxyl groups generated by hydrolysis in the silanol solution and the dissolved silane oligomers are dispersed into droplets or aggregates of nanometer to micrometer scale by mechanical shear force and are uniformly distributed in the continuous aqueous phase of the hybrid emulsion. The silanol hydroxyl groups undergo hydrogen bonding adsorption with the polar groups (such as carboxyl groups and hydroxyl groups) on the surface of the polymer particles of the hybrid emulsion, forming an initial physical bond. At the same time, the subsequently added aluminum acetylacetone catalyst is also uniformly dispersed in the entire system. This catalyst exhibits mild latency characteristics for silanol condensation at room temperature, which can effectively ensure that the composite coating has the necessary storage stability and application period. After stirring, a milky white liquid with a uniform and stable appearance and no visible phase separation or coarse particles is obtained, which is the composite coating.

[0037] It is understood that this step, by achieving uniform and stable dispersion of the multi-component system and controllable latency of the reaction precursor, plays a role in constructing a homogeneous, stable composite coating with a preset reaction path. This composite coating provides a starting point with uniform composition and properties for subsequent coating and programmed curing processes. The uniformity ensures that functional silanes (including KH-560, PEG-Si, and MTMS) exist at similar concentrations at any location in the wet film to be coated. This is a prerequisite for the final formation of a controllable, non-sharp gradient distribution structure, rather than a random phase separation structure, through the curing process. The stability ensures that the composite coating will not undergo significant silanol condensation gelation before application. That is, the mild activity of the aluminum acetylacetonate catalyst at room temperature effectively inhibits the condensation reaction of silanols, thus enabling the coating to have the necessary storage and application period.

[0038] Understandably, the composite coating acquisition steps provide a guarantee for ensuring the reproducibility and reliability of solving the problem of hydrophilic component loss. If the functional silane is not uniformly dispersed in the coating, the hydrophilic component PEG-Si may be locally enriched or depleted during subsequent curing, resulting in uneven hydrophilicity of the coating. In some areas where PEG-Si is depleted, the anti-corrosion network may be directly exposed, forming weak points in performance. More importantly, uneven dispersion can cause excessive local phase separation during curing, resulting in interface defects. By controlling the stirring speed, feeding sequence, and time, it is ensured that PEG-Si forms a highly uniform initial dispersion with other silanes and polymer particles in the hybrid emulsion. This allows PEG-Si to regularly participate in the network construction of the entire coating during subsequent pre-curing and programmed temperature curing, thereby ensuring the universality and thoroughness of its chemical anchoring. This avoids localized poor encapsulation or network leakage caused by uneven initial dispersion, and enables the solution of preventing loss through chemical bonding to be fully and consistently implemented throughout the entire coating.

[0039] It is worth noting that this step employs a process of first adding a silanol solution to the hybrid emulsion, followed by the catalyst, and controlling the stirring speed in stages to treat the materials. This achieves uniform mixing while maximizing the maintenance of the system's chemical stability before application and obtaining a suitable rheological state. The 40-60% solid content of the hybrid emulsion provides the basic solids and viscosity basis for film formation. The 1:(1.5-4) mass ratio of total solids in the silanol solution to solids in the hybrid emulsion balances the ratio of the inorganic silicon network to the organic resin phase. Too high a ratio may lead to increased coating brittleness, while too low a ratio may affect gradient formation and corrosion resistance. Adding the silanol solution at 300-500 rpm over 5-10 minutes can overcome interfacial tension to achieve good dispersion, while avoiding excessive air bubbles introduced by excessively rapid stirring or causing... Emulsion demulsification, followed by adding aluminum acetylacetonate catalyst and then reducing the stirring speed to 100-200 rpm and maintaining this speed for 25-35 minutes, helps eliminate bubbles, promotes further uniform diffusion of components, and establishes weak interactions such as hydrogen bonds, thereby improving the storage stability of the coating. This process avoids damaging the already formed metastable dispersion structure or inducing premature reactions due to excessive shear force. The addition of aluminum acetylacetonate also provides moderate catalytic potential, ensuring sufficient latency at room temperature and effective catalytic condensation during the temperature curing stage. Aluminum acetylacetonate is chosen as the catalyst because it exhibits mild catalytic activity for silanol condensation at room temperature, which is beneficial for the storage stability of the composite coating. During the temperature curing stage, its catalytic efficiency is significantly improved, effectively promoting the formation of siloxane networks.

[0040] Specifically, in step S2, the surface of the substrate is pretreated to give it active hydroxyl groups, and the composite coating is applied to the substrate to form a wet film. Step S2 specifically includes the following steps: Step S21: Degrease and clean the metal substrate, and perform sandblasting or phosphating treatment as needed to make its surface clean and have active hydroxyl groups, thus obtaining the first substrate. Step S22: Apply the composite coating evenly to the pretreated substrate using a spraying process to form a wet film with a thickness of 80-100μm on the substrate. After the wet film is formed, let the substrate stand at room temperature for 3-5 minutes to level it, and obtain the second substrate.

[0041] It should be noted that in step S2, the material undergoes a physical transformation process from an independent solid substrate and liquid composite coating to a composite wet film system with a specific geometry and initial distribution formed by the combination of the two. This step includes two stages: surface activation and physical film formation. In this step, the surface contaminants of the metal substrate, after degreasing, cleaning, and optional sandblasting or phosphating, are removed, while the specific surface area increases and more fresh, highly reactive metal hydroxyl groups are exposed. When the composite coating is applied to the activated surface of the first substrate through a spraying process, the components in the coating, including polymer particles in the hybrid emulsion, dissolved and dispersed silanol molecules, catalysts, etc., spread on the surface of the first substrate and form a continuous liquid film. In the subsequent static leveling stage, as the solvent partially evaporates, the solid content inside the wet film gradually increases, and small molecules such as silanol begin to diffuse and accumulate in the liquid-solid (substrate) interface region due to interfacial adsorption. After the composite coating is applied, a uniform wet film coating with a basically flat surface, a certain thickness and gloss is formed, and its physical state is a flowable or semi-flowable liquid.

[0042] It is known that step S2, through effective cleaning and chemical activation of the substrate surface and uniform and continuous coating of the composite coating to form a wet film of controllable thickness, creates an ideal and consistent physical interface and initial morphology for the entire coating. This effect lays an indispensable physical foundation for the chemical reaction and structure formation in subsequent steps. The clean and active hydroxyl-rich surface of the first substrate is a prerequisite for ensuring that the KH-560 component in the silanol can form effective chemical bonds to form Si-O-Me bonds. This directly determines the final adhesion and corrosion resistance of the coating. The uniform coating of the composite coating with a thickness of 80-100μm establishes the basic geometric dimensions of the coating and ensures the uniformity of the initial distribution of functional components such as PEG-Si in the two-dimensional plane. This creates the initial conditions for the formation of a non-uniform distribution of functional components in the coating thickness direction, i.e., a gradient structure tendency, by taking advantage of the difference in solvent evaporation and reaction kinetics during the subsequent curing process.

[0043] Understandably, the above steps create favorable initial conditions to ensure the resolution of the hydrophilic component loss problem. If the substrate pretreatment is insufficient, and there is oil or an inert oxide layer on the surface, the subsequent interfacial chemical bonding of KH-560 will be difficult to achieve, leading to a decrease in the overall adhesion of the coating. Under environmental stress, the coating is prone to peeling off from the substrate. At this point, no matter how firmly PEG-Si is anchored in the coating network, the failure of the entire coating system will result in the simultaneous loss of hydrophilic and anti-corrosion functions. Therefore, a strong interfacial bond is a prerequisite for the long-term service of the entire coating system. Simultaneously, the uniformity of the wet film thickness... Uniformity is crucial. Uneven thickness can lead to inconsistent solvent evaporation rates and heat transfer during subsequent curing, potentially causing differences in the distribution of the silanol gradient and the degree of curing. Areas that are too thin cannot form a complete gradient structure, while areas that are too thick will have weaknesses due to poor internal curing. This structural inhomogeneity can become a defect in the local anti-corrosion barrier and also affect the uniformity of PEG-Si chemical anchoring. Therefore, the above steps, through standardized pretreatment and coating processes, lay the foundation for building a system with a strong interface and uniform initial distribution, thereby supporting the subsequent fixation of hydrophilic components through chemical bonding.

[0044] It is worth noting that step S2 employs pretreatment, including sandblasting / phosphating, and spraying and leveling processes to treat the material, maximizing the optimization of the substrate state and controlling the initial morphology and thickness of the coating to ensure the reliability and reproducibility of the process. Degreasing, cleaning, and sandblasting or phosphating of the metal substrate aim to remove contaminants affecting adhesion. Physical sandblasting roughening or chemical phosphating to generate a porous phosphate film significantly increases the active area and reactive sites on the substrate surface, enhancing the strength and reliability of interfacial chemical bonding. Using a spraying process and controlling the wet film thickness to 80-100 μm achieves a coating thickness that balances performance and economy. This thickness range ensures the formation of a sufficiently continuous and dense protective layer while avoiding problems such as increased internal stress, incomplete curing, and increased costs caused by excessive thickness. Furthermore, allowing the coating to stand at room temperature for 3-5 minutes after coating allows the wet film to level naturally under gravity, eliminating surface unevenness or orange peel effects caused by spraying, resulting in a smoother surface. This facilitates uniform heating during subsequent curing and reduces abnormal local component distribution caused by differences in surface tension.

[0045] Specifically, in step S3, the substrate coated with the wet film is pre-cured and then heated to cure. After curing, a hydrophilic and anti-corrosion integrated coating is formed on the substrate.

[0046] Step S3 specifically includes the following steps: Step S31: Place the second substrate in an oven and heat-cur it at a first temperature for 28-32 minutes, so that the wet film on the second substrate is converted into a dry gel state; in step S31, the first temperature is 58-62℃. Step S32: After raising the first temperature to the second temperature at a rate of 2-3℃ / min, the second substrate is held at the second temperature for 55-65min, and then naturally cooled to room temperature; in step S32, the second temperature is 118-122℃.

[0047] It should be noted that in step S3, the material undergoes a fundamental change from a liquid wet film through physical state transformation and complex chemical reactions to finally form a solid cross-linked network coating. This step, through a phased process of low-temperature pre-curing followed by high-temperature curing, utilizes the kinetic differences between solvent evaporation, interfacial reactions, and overall network condensation to regulate the distribution and fixation order of functional components. In the pre-curing stage, the temperature is controlled at a first temperature of 58-62℃. At this first temperature, water and ethanol solvents evaporate rapidly, leading to a sharp increase in system concentration. Simultaneously, this first temperature is lower than the typical temperature for rapid condensation of silanol, effectively suppressing premature formation of the bulk network. At this point, KH enriched at the interface of the second substrate... 560 silanol undergoes condensation with metal hydroxyl groups to form preliminary Si. O Me chemical anchoring occurs, and initial condensation begins between silanols to form an early Si-O-Si network, transforming the system from a liquid to a dry gel state. During the subsequent curing stage, the temperature rises to 118-122℃, driving the complete escape of residual solvent and, more importantly, providing a higher activation energy. The aluminum acetylacetonate catalyst activity is significantly enhanced, accelerating the condensation reaction between all silanols (from KH-560, PEG-Si, and MTMS), forming a highly cross-linked, dense three-dimensional Si-O-Si inorganic network. Simultaneously, the acrylic-siloxane polymer chains in the hybrid emulsion and the grown Si-O-Si network are physically entangled and interact with each other, forming an organic-inorganic hybrid coating structure. Furthermore, the hydrophilic function... The silanols at one or both ends of the PEG-Si component also participate in the condensation and crosslinking of the overall network, thereby chemically anchoring the entire polyethylene glycol hydrophilic segments to the coating skeleton through covalent bonds. During the solvent evaporation and system concentration process in the pre-curing stage, due to the differences in polarity, surface energy, and interaction with the solvent among the components, PEG-Si tends to accumulate on the surface of the coating. The subsequent high-temperature curing causes the entire network to crosslink and solidify rapidly, thereby freezing and fixing this non-uniform distribution state, and finally achieving relative enrichment of PEG-Si on the surface of the coating. In this process, the coating changes from a flowable wet film to a dry gel, and finally, after high-temperature curing, forms a hard, smooth, transparent or translucent solid coating that adheres firmly to the second substrate.

[0048] It is known that step S3 controls and completes the transformation of the coating from a physical mixture to a chemical entity, which is the final molding step to achieve integrated hydrophilic and anti-corrosion performance. The pre-curing stage mainly completes the strong fixation of the interface and the initial network construction, locking the basic morphology of the coating and initiating the chemical reaction. The subsequent temperature curing achieves high cross-linking of the network and locks in the functional distribution. The staged temperature control of this method avoids problems such as large amount of solvent evaporation and bubble generation caused by rapid one-time high-temperature curing, stress cracking caused by excessively fast reaction, or thermal degradation of hydrophilic segments, thus ensuring the integrity of the coating quality and the optimization of its performance.

[0049] Understandably, step S3 effectively solves the problem of loss caused by physical blending of hydrophilic components. This step is the final execution step to achieve chemical bonding fixation. In this process, the silanol ends of the hydrophilic component PEG-Si, together with other silane components, participate in a comprehensive condensation crosslinking reaction, forming a unified Si-O-Si network. This indicates that the hydrophilic segments of polyethylene glycol, through their terminal siloxane bonds, become an inseparable part of the entire three-dimensional crosslinked network. They are fixed by strong covalent bonds, rather than the weak van der Waals forces or mechanical encapsulation in traditional physical blending. Therefore, in subsequent service environments, the scouring or soaking of water or other media is unlikely to cause it to dissolve or fall off in large quantities from the coating body, thus effectively suppressing performance degradation and possible structural defects caused by physical loss of hydrophilic components. At the same time, the highly crosslinked and dense Si-O-Si network itself provides excellent barrier properties, effectively blocking the penetration of water, oxygen, and corrosive ions, thereby achieving a balance between long-term maintenance of hydrophilic function and reliable protection of corrosion resistance.

[0050] It is worth noting that step S3 employs a two-stage process of low-temperature pre-curing followed by high-temperature curing. This effectively controls the reaction kinetics and the sequence of physical changes to match the scientific laws governing coating structure formation and obtain a defect-free, high-quality coating. In the pre-curing stage, a first temperature of 58-62℃ is maintained for 28-32 minutes, allowing the solvents, primarily water and ethanol, to evaporate rapidly, enabling the wet film to quickly reach its gel point, fixing its initial morphology and initiating interfacial bonding. This temperature is also significantly lower than the temperatures at which silane undergoes vigorous condensation and PEG segments undergo significant thermal degradation, thus avoiding over-reaction. In the high-temperature curing stage, the temperature is increased to 118-122℃. The second temperature, with a slow heating rate of 2-3℃ / min, helps the internal temperature of the coating to rise uniformly, reducing the risk of cracking due to thermal stress. At the same time, holding the second temperature for 55-65 minutes ensures that the silanol condensation reaction is sufficient and thorough, achieving the highest crosslinking density, thereby maximizing the coating's hardness, adhesion, and chemical resistance. Meanwhile, the range of the second temperature and the holding time are within the thermal stability window of the polyethylene glycol segments, avoiding excessive thermal oxidation of the hydrophilic components. Under the combined effect of the above methods, the formation of a gradient structure coating, from the gel network to the final highly cured coating with surface hydrophilicity and overall anti-corrosion function, is ensured.

[0051] The following table shows the corresponding data for the hydrophilic anti-corrosion integrated coating obtained in Example 1 and the traditional hydrophilic anti-corrosion coating. Please refer to Table 1 for details: Table 1 The test data of the control group in Table 1 are the average values ​​after multiple tests of the traditional hydrophilic anticorrosive coating. The preparation method of the traditional hydrophilic anticorrosive coating is as follows: First, bisphenol A type epoxy resin (E-51) as the anticorrosive matrix is ​​mixed with polyethylene glycol (PEG-600) as the hydrophilic agent and part of the solvent propylene glycol methyl ether acetate (PMA). The hydrophilic agent is dissolved and dispersed in the resin by mechanical stirring. Then, polyamide curing agent (651) and the remaining solvent are added and stirring is continued to form a uniform coating. After a short curing period, it is coated onto the pretreated substrate using a wire bar coater, and the wet film thickness is controlled to be about 100 μm. Finally, the coating is cured at 80°C for 2 hours. In this method, the hydrophilic agent and the resin matrix are only physically and mechanically mixed and bonded. The hydroxyl groups of polyethylene glycol do not undergo effective chemical reaction with the epoxy-amine curing system. Therefore, its interfacial bonding is weak, and its performance is easily degraded due to the loss of hydrophilic components during service.

[0052] The data in Table 1 for the embodiments were obtained based on three specific embodiments a, b, and c. Specific example a is as follows: Step S1: KH-560, PEG-Si, and MTMS are added sequentially to the reaction vessel in a molar ratio of 2.5:4.5:1.7. Then, a mixed solvent of deionized water and anhydrous ethanol is added in a volume ratio of 1:3.8, controlling the total silane concentration to 20 wt%. Acetic acid is added dropwise during stirring to adjust the pH of the system to 4.0, and the mixture is continuously stirred at 300 rpm for 110 min at room temperature to obtain a homogeneous silanol solution. The PEG-Si used is synthesized according to the following steps: polyethylene glycol with a molecular weight of 600 is mixed with anhydrous tetrahydrofuran in a mass ratio of 1:2.5 and kept at 58°C for 30 min to ensure complete dissolution. The system is then cooled to 38°C, and isocyanate-propyltrimethoxysilane (molar ratio to polyethylene glycol 1:2.05) is added dropwise at a uniform rate over 30 min. After the addition is complete, 0.5% of the polyethylene glycol mass is added. A 0.05% dibutyltin dilaurate catalyst was used; the system temperature was then raised to 63℃, and the reaction was stirred at this temperature for 4 hours; after the reaction was completed, the system was cooled to room temperature, and rotary evaporation was performed at 45℃ to remove most of the solvent. Then, it was dried at 40℃ and a vacuum degree of not less than 0.095MPa for 24 hours to obtain the target product PEG-Si; in a dispersion vessel, an aqueous acrylic-siloxane hybrid emulsion with a solid content of 40% was stirred at a stirring speed of 300 rpm; the silanol solution prepared above was slowly added over 5 minutes, and the ratio of the total solid mass of silane in the silanol solution to the solid mass of the hybrid emulsion was controlled to be 1:1.5; after the addition was completed, aluminum acetylacetonate catalyst accounting for 0.3% of the solid mass of the hybrid emulsion was added; after adding the catalyst, the stirring speed was reduced by 100 rpm to 200 rpm, and stirring was continued for 25 minutes to ensure that the components were fully mixed and dispersed to obtain a uniform and stable composite coating.

[0053] Step S2: Degrease, clean and sandblast the aluminum alloy substrate to make its surface clean and have active hydroxyl groups; use a spraying process to uniformly coat the composite coating on the treated substrate surface to form a coating with a wet film thickness of 80μm; after coating, let the substrate stand at room temperature for 3 minutes to level.

[0054] Step S3: Place the coated substrate in an oven and pre-cur it at 58°C for 28 minutes to convert the wet film into a dry gel state. Then, increase the oven temperature from the first temperature to 118°C at a rate of 2°C / min and maintain it at 118°C for 55 minutes for final curing. After curing, allow the workpiece to cool naturally to room temperature with the oven, thus forming a hydrophilic and anti-corrosion integrated coating on the substrate.

[0055] The performance test results of the coating in Example a are as follows: the initial water contact angle is 9°, exhibiting superhydrophilic properties; after a neutral salt spray test, its corrosion resistance time reaches 1000 hours, and the coating surface shows no blistering or rust after the test, demonstrating excellent corrosion resistance; the cross-cut adhesion test result is Grade 1, indicating that the coating is very firmly bonded to the substrate; to evaluate the durability of the hydrophilic function, after immersing the coating in deionized water at 80°C for 7 days, its water contact angle only slightly increases to 14°, proving that the loss of hydrophilic components is minimal; in addition, after 1000 steel wool abrasion tests, the coating surface remains intact without damage, and the contact angle after the test is 19°, indicating that it has good mechanical durability; all performance data of Example a are significantly better than those of traditional physical blend coatings, effectively solving the technical problem of hydrophilic components being lost due to weak physical bonding and causing synergistic failure.

[0056] According to the test data of Example a, this example pre-hydrolyzes the terminal silane of the hydrophilic component PEG-Si together with other silanes (KH-560, MTMS), so that all components have the same silanol reactivity at the molecular level. In the subsequent curing process, PEG-Si is firmly anchored in the three-dimensional Si-O-Si network in the form of covalent bonds through siloxane condensation reaction, eliminating physical loss. The slight difference between its initial contact angle of 9° and the contact angle of 14° after dry heat immersion directly proves the durability of the hydrophilic function. At the same time, the dense hybrid network ensures excellent anti-corrosion performance of salt spray 1000 and Grade 1 adhesion, successfully solving the vicious cycle problem of performance synergistic failure caused by component loss in traditional coatings.

[0057] Example b is as follows: Step S1: KH-560, PEG-Si, and MTMS are added sequentially to the reaction vessel in a molar ratio of 3.0:5.0:2.0. Then, a mixed solvent of deionized water and anhydrous ethanol is added in a volume ratio of 1:4.0, controlling the total silane concentration to 25 wt%. Acetic acid is added dropwise during stirring to adjust the pH of the system to 4.5, and the mixture is continuously stirred at 450 rpm for 120 min at room temperature to obtain a homogeneous silanol solution. The PEG-Si used is synthesized according to the following steps: polyethylene glycol with a molecular weight of 600 is mixed with anhydrous tetrahydrofuran in a mass ratio of 1:3.5 and kept at 60°C for 30 min to ensure complete dissolution. The system is then cooled to 40°C, and isocyanate-propyltrimethoxysilane (molar ratio to polyethylene glycol 1:2.15) is added dropwise at a uniform rate over 30 min. After the addition is complete, 0.12% of the polyethylene glycol mass is added. A % dibutyltin dilaurate catalyst was added; the system temperature was then raised to 65℃, and the reaction was stirred at this temperature for 5 hours; after the reaction was completed, the system was cooled to room temperature, and rotary evaporation was performed at 47℃ to remove most of the solvent. Then, it was dried at 40℃ and a vacuum degree of not less than 0.095MPa for 24 hours to obtain the target product PEG-Si; in a dispersion vessel, an aqueous acrylic-siloxane hybrid emulsion with a solid content of 50% was stirred at a stirring speed of 400 rpm; the silanol solution prepared above was slowly added over 7.5 minutes, and the ratio of the total solid mass of silane in the silanol solution to the solid mass of the hybrid emulsion was controlled to be 1:2.75; after the addition was completed, aluminum acetylacetonate catalyst accounting for 0.65% of the solid mass of the hybrid emulsion was added; after the catalyst was added, the stirring speed was reduced by 150 rpm to 250 rpm, and stirring was continued for 30 minutes to ensure that the components were fully mixed and dispersed to obtain a uniform and stable composite coating.

[0058] Step S2: Degrease, clean and sandblast the aluminum alloy substrate to make its surface clean and have active hydroxyl groups; use a spraying process to uniformly coat the composite coating on the treated substrate surface to form a coating with a wet film thickness of 90μm; after coating, let the substrate stand at room temperature for 4 minutes to level.

[0059] Step S3: Place the coated substrate in an oven and pre-cur it at 60°C for 30 minutes to convert the wet film into a dry gel state. Then, increase the oven temperature from the first temperature to 120°C at a rate of 2.5°C / min and maintain it at 120°C for 60 minutes for final curing. After curing, allow the workpiece to cool naturally to room temperature with the oven, thus forming a hydrophilic and anti-corrosion integrated coating on the substrate.

[0060] The coating performance test results for Example b are as follows: the initial water contact angle was as low as 6°, showing good surface wettability; the salt spray test showed that the coating remained intact after 1250 hours, with no signs of corrosion, demonstrating significant anti-corrosion performance; the cross-cut adhesion test reached the highest level 0, proving the extremely strong bonding force between the coating and the substrate; after 7 days of accelerated aging in water at 80°C, the contact angle of the coating only increased to 10°, exhibiting excellent hydrophilicity retention, far superior to the control group; after the abrasion test, the coating remained intact with a contact angle of 16°, demonstrating excellent durability.

[0061] According to the test data of Example b, this example achieves the best balance between hydrophilic function and anti-corrosion structure under optimized process parameters. The initial contact angle of 6° and the contact angle of 10° after aging in this example indicate that the surface hydrophilic component concentration is high and the bonding is extremely strong. Its salt spray resistance time is as long as 1250h, and the adhesion reaches the highest level 0. The overall performance is the most outstanding. This is attributed to the fact that the parameters such as silane ratio, curing temperature and time are in the optimal range, so that the chemical anchoring efficiency of PEG-Si, the crosslinking density of Si-O-Si network and the interfacial bonding strength are all optimal.

[0062] Implementation example c is as follows: Step S1: KH-560, PEG-Si, and MTMS are added sequentially to the reaction vessel in a molar ratio of 3.5:5.5:2.3. Then, a mixed solvent of deionized water and anhydrous ethanol is added in a volume ratio of 1:4.2, controlling the total silane concentration to 30 wt%. Acetic acid is added dropwise during stirring to adjust the pH of the system to 5.0, and the mixture is continuously stirred at 600 rpm for 130 min at room temperature to obtain a homogeneous silanol solution. The PEG-Si used is synthesized according to the following steps: polyethylene glycol with a molecular weight of 600 is mixed with anhydrous tetrahydrofuran in a mass ratio of 1:4.5 and kept at 62°C for 30 min to ensure complete dissolution. The system is then cooled to 42°C, and isocyanate-propyltrimethoxysilane (molar ratio to polyethylene glycol 1:2.25) is added dropwise at a uniform rate over 30 min. After the addition is complete, 0.5% of the polyethylene glycol mass is added. A 2% dibutyltin dilaurate catalyst was added; the system temperature was then raised to 67°C, and the reaction was stirred at this temperature for 6 hours; after the reaction was completed, the system was cooled to room temperature, and rotary evaporation was performed at 50°C to remove most of the solvent. Subsequently, it was dried at 40°C under a vacuum of not less than 0.095 MPa for 24 hours to obtain the target product PEG-Si; in a dispersion vessel, an aqueous acrylic-siloxane hybrid emulsion with a solid content of 60% was stirred at a stirring speed of 500 rpm; the silanol solution prepared above was slowly added over 10 minutes, controlling the ratio of the total solid mass of silane in the silanol solution to the solid mass of the hybrid emulsion to be 1:4.0; after the addition was completed, aluminum acetylacetonate catalyst accounting for 1.0% of the solid mass of the hybrid emulsion was added; after adding the catalyst, the stirring speed was reduced by 200 rpm to 300 rpm, and stirring was continued for 35 minutes to ensure that the components were fully mixed and dispersed to obtain a uniform and stable composite coating.

[0063] Step S2: Degrease, clean and sandblast the aluminum alloy substrate to make its surface clean and have active hydroxyl groups; use a spraying process to uniformly coat the treated substrate surface with composite coating to form a wet film thickness of 100μm; after coating, let the substrate stand at room temperature for 5 minutes to level.

[0064] Step S3: Place the coated substrate in an oven and pre-cur it at 62°C for 32 minutes to convert the wet film into a dry gel state. Then, increase the oven temperature from the first temperature to 122°C at a rate of 3°C / min and maintain it at 122°C for 65 minutes for final curing. After curing, allow the workpiece to cool naturally to room temperature with the oven, thus forming a hydrophilic and anti-corrosion integrated coating on the substrate.

[0065] The coating performance test results for Example c are as follows: the initial water contact angle is 8°, indicating excellent hydrophilicity; the salt spray resistance time reached 1100h, and the coating remained intact, demonstrating reliable anti-corrosion performance; the cross-cut adhesion test result was Grade 1, indicating that the coating adhered firmly; after aging by immersion in water at 80℃, the contact angle was 13°, and the hydrophilicity remained stable without significant attenuation; after 1000 abrasion tests, the coating did not break, and the contact angle after the test was 18°, showing sufficient mechanical strength.

[0066] According to the test data of Example c, the coating prepared in this example has a contact angle of 8°, a salt spray resistance of 1100h, and an adhesion grade of 1, indicating that this example has a wide process window and good operational flexibility. The key is that by following the co-hydrolysis and chemical anchoring of silane, even under high solid content and high concentration conditions, the hydrophilic component PEG-Si can still be effectively integrated into the network, without the exacerbation of phase separation and loss under high load as in physical blending.

[0067] Example 2: The hydrophilic and anti-corrosion integrated coating in this embodiment is prepared by the preparation method described in Example 1.

[0068] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an integrated hydrophilic and anti-corrosion coating, characterized in that, The preparation method includes the following steps: Step S1: Hydrolyze various trimethoxysilanes in an acidic aqueous solution to obtain a silanol solution with silanol groups. Then, add the silanol solution and the catalyst to the hybrid emulsion in sequence and stir to obtain a composite coating. Step S2: Pre-treat the surface of the substrate to make it have active hydroxyl groups, and then apply the composite coating to the substrate to form a wet film; Step S3: After pre-curing the substrate coated with wet film, heat it up to cure it. After curing, a hydrophilic and anti-corrosion integrated coating is formed on the substrate.

2. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 1, characterized in that, The silanol solution is obtained according to the following steps: First, KH-560, PEG-Si and MTMS were added to the reaction vessel, followed by the addition of a mixed solvent. Acetic acid was added dropwise during stirring to adjust the pH of the system to 4.0-5.

0. The system was then stirred at 300-600 rpm for 110-130 min at room temperature under this pH value. After stirring, a silanol solution was obtained.

3. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 2, characterized in that, The molar ratio of KH-560, PEG-Si and MTMS is (2.5-3.5):(4.5-5.5):(1.7-2.3), the mixed solvent includes deionized water and anhydrous ethanol, and the volume ratio of deionized water to anhydrous ethanol is 1:(3.8-4.2), and the concentration of silane in the silanol solution is 20-30wt%.

4. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 3, characterized in that, The PEG-Si is obtained according to the following steps: Polyethylene glycol and anhydrous tetrahydrofuran were kept at 58-62℃ for 30 min, then the system was cooled to 38-42℃, and isocyanate-based propyltrimethoxysilane was added dropwise over 30 min, followed by the addition of dibutyltin dilaurate catalyst. The system temperature was then raised to 63-67℃ and stirred for 4-6 h. After stirring, the system was cooled to room temperature and evaporated at 45-50℃, then dried in a vacuum environment of 40℃ and ≥0.095 MPa for 24 h to obtain PEG-Si. The molecular weight of polyethylene glycol was 600, the molar ratio of polyethylene glycol to isocyanate-based propyltrimethoxysilane was 1:(2.05-2.25), the mass ratio of anhydrous tetrahydrofuran to polyethylene glycol was (2.5-4.5):1, and the amount of dibutyltin dilaurate catalyst added was 0.05%-0.2% of the mass of polyethylene glycol.

5. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 4, characterized in that, The composite coating is obtained according to the following steps: The hybrid emulsion is stirred at 300-500 rpm in a dispersion vessel. A silanol solution is added after 5-10 min. After the silanol solution is added, a catalyst is added, and the stirring speed is reduced by 100-200 rpm and stirred for 25-35 min to obtain the composite coating.

6. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 5, characterized in that, The hybrid emulsion is an aqueous acrylic-siloxane hybrid emulsion with a solid content of 40-60%. The catalyst is aluminum acetylacetonate, and the amount of aluminum acetylacetonate added is 0.3%-1.0% of the solid mass of the hybrid emulsion. The ratio of the total solid mass of silane in the silanol solution to the solid mass of the hybrid emulsion is 1:(1.5-4).

7. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 1, characterized in that, Step S2 specifically includes the following steps: Step S21: Degrease and clean the metal substrate, and perform sandblasting or phosphating treatment as needed to make its surface clean and have active hydroxyl groups, thus obtaining the first substrate. Step S22: Apply the composite coating evenly to the pretreated substrate using a spraying process to form a wet film with a thickness of 80-100μm on the substrate. After the wet film is formed, let the substrate stand at room temperature for 3-5 minutes to level it, and obtain the second substrate.

8. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 7, characterized in that, Step S3 specifically includes the following steps: Step S31: Place the second substrate in an oven and heat-cur it at the first temperature for 28-32 minutes, so that the wet film on the second substrate is transformed into a dry gel state. Step S32: After raising the first temperature to the second temperature at a rate of 2-3℃ / min, the second substrate is held at the second temperature for 55-65min, and then naturally cooled to room temperature.

9. The method for preparing the hydrophilic and anti-corrosion integrated coating according to claim 8, characterized in that, In step S31, the first temperature is 58-62℃, and in step S32, the second temperature is 118-122℃.

10. A hydrophilic and anti-corrosion integrated coating, characterized in that, The hydrophilic and anti-corrosion integrated coating is prepared by the method described in any one of claims 1-9.

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